Optimization of non-coding regions for a non-modified mRNA COVID-19 vaccine.

The CVnCoV (CureVac) mRNA vaccine for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was recently evaluated in a phase 2b/3 efficacy trial in humans1. CV2CoV is a second-generation mRNA vaccine containing non-modified nucleosides but with optimized non-coding regions and enhanced antigen expression. Here we report the results of a head-to-head comparison of the immunogenicity and protective efficacy of CVnCoV and CV2CoV in non-human primates. We immunized 18 cynomolgus macaques with two doses of 12 µg lipid nanoparticle-formulated CVnCoV or CV2CoV or with sham (n = 6 per group). Compared with CVnCoV, CV2CoV induced substantially higher titres of binding and neutralizing antibodies, memory B cell responses and T cell responses as well as more potent neutralizing antibody responses against SARS-CoV-2 variants, including the Delta variant. Moreover, CV2CoV was found to be comparably immunogenic to the BNT162b2 (Pfizer) vaccine in macaques. Although CVnCoV provided partial protection against SARS-CoV-2 challenge, CV2CoV afforded more robust protection with markedly lower viral loads in the upper and lower respiratory tracts. Binding and neutralizing antibody titres were correlated with protective efficacy. These data demonstrate that optimization of non-coding regions can greatly improve the immunogenicity and protective efficacy of a non-modified mRNA SARS-CoV-2 vaccine in non-human primates.

Tunability of DNA Polymerase Stability during Eukaryotic DNA Replication.

Structural and biochemical studies have revealed the basic principles of how the replisome duplicates genomic DNA, but little is known about its dynamics during DNA replication. We reconstitute the 34 proteins needed to form the S. cerevisiae replisome and show how changing local concentrations of the key DNA polymerases tunes the ability of the complex to efficiently recycle these proteins or to dynamically exchange them. Particularly, we demonstrate redundancy of the Pol α-primase DNA polymerase activity in replication and show that Pol α-primase and the lagging-strand Pol δ can be re-used within the replisome to support the synthesis of large numbers of Okazaki fragments. This unexpected malleability of the replisome might allow it to deal with barriers and resource challenges during replication of large genomes.

Rapid single-molecule characterisation of enzymes involved in nucleic-acid metabolism.

The activity of enzymes is traditionally characterised through bulk-phase biochemical methods that only report on population averages. Single-molecule methods are advantageous in elucidating kinetic and population heterogeneity but are often complicated, time consuming, and lack statistical power. We present a highly-generalisable and high-throughput single-molecule assay to rapidly characterise proteins involved in DNA metabolism. The assay exclusively relies on changes in total fluorescence intensity of surface-immobilised DNA templates as a result of DNA synthesis, unwinding or digestion. Combined with an automated data-analysis pipeline, our method provides enzymatic activity data of thousands of molecules in less than an hour. We demonstrate our method by characterising three fundamentally different enzyme activities: digestion by the phage λ exonuclease, synthesis by the phage Phi29 polymerase, and unwinding by the E. coli UvrD helicase. We observe the previously unknown activity of the UvrD helicase to remove neutravidin bound to 5'-, but not 3'-ends of biotinylated DNA.

femtoPro: virtual-reality interactive training simulator of an ultrafast laser laboratory.

The huge field of optics and photonics research and development is in constant demand of well-trained experts. However, it is challenging to teach efficiently the setup process of complicated optical experiments due to limited hardware availability and eye-safety concerns, in particular, in the case of femtosecond lasers. We have developed an interactive simulation of an ultrafast laser laboratory ("femtoPro") for teaching and training, implementing physical models for the calculation and visualization of Gaussian laser beam propagation, ultrashort optical pulses, their modulation by typical optical elements, and linear as well as nonlinear light-matter interaction. This facilitates the setup and simulated measurement procedure, in virtual reality (VR) and at real-time speeds, of various typical optical arrangements and spectroscopy schemes such as telescopes, interferometers, or pulse characterization. femtoPro can be employed to supplement academic teaching in connection with regular courses in optics or spectroscopy, to train future scientists and engineers in the field of (ultrafast) optics in practical skills, to communicate to other researchers how to set up and align a particular experiment, to "test-build" and simulate new designs of optical setups, to simulate ultrafast spectroscopy data, to offer practical exercises to high-school students, and to reach out to the general public.

Replisome bypass of a protein-based R-loop block by Pif1.

Efficient and faithful replication of the genome is essential to maintain genome stability. Replication is carried out by a multiprotein complex called the replisome, which encounters numerous obstacles to its progression. Failure to bypass these obstacles results in genome instability and may facilitate errors leading to disease. Cells use accessory helicases that help the replisome bypass difficult barriers. All eukaryotes contain the accessory helicase Pif1, which tracks in a 5'-3' direction on single-stranded DNA and plays a role in genome maintenance processes. Here, we reveal a previously unknown role for Pif1 in replication barrier bypass. We use an in vitro reconstituted Saccharomyces cerevisiae replisome to demonstrate that Pif1 enables the replisome to bypass an inactive (i.e., dead) Cas9 (dCas9) R-loop barrier. Interestingly, dCas9 R-loops targeted to either strand are bypassed with similar efficiency. Furthermore, we employed a single-molecule fluorescence visualization technique to show that Pif1 facilitates this bypass by enabling the simultaneous removal of the dCas9 protein and the R-loop. We propose that Pif1 is a general displacement helicase for replication bypass of both R-loops and protein blocks.

[Prehospital stroke treatment in German-speaking countries]. / Praxis der präklinischen Schlaganfallversorgung im deutschsprachigen Raum: Eine Umfrage unter den ärztlichen Leitungen Rettungsdienst in Deutschland, Österreich und der Schweiz.

Background: The prognosis of stroke patients can be improved by adherence to clinical guidelines. Objective: To analyse the current state of organisation of prehospital stroke treatment in Germany, Austria and Switzerland with a focus on guideline adherence. Materials and methods: All medical directors of emergency medical services (MDEMS) in Germany (n = 178), Austria (n = 9) and Switzerland (n = 32) were invited to complete an anonymous online survey (unipark.com, Tivian XI GmbH, Cologne, Germany) which was available for 10 weeks from April-June 2020. Participants were asked for information regarding structural organisation, clinical treatment and strategic/tactical aspects. Results: The survey was completed 69 times and 65 datasets were analysed (4 participants without MDEMS status): 73.8% (n = 48) were MDEMS from Germany, 15.4% (n = 10) from Switzerland and 10.8% from Austria (n = 7). The survey results show relevant differences in the infrastructure of and the approach to prehospital stroke treatment. Standard operating procedures for stroke treatment were in place in 93.3% (n = 61) of the EMS areas. Furthermore, 37% (n = 24) of the EMS areas differentiated between stroke with mild and severe symptoms and 15.4% (n = 10) used specific scores for the prehospital prediction of large vessel occlusion strokes (LVOS). Conclusions: Our data highlight the heterogeneity of prehospital stroke treatment in Germany, Austria and Switzerland. Consistent use of appropriate scores for LVOS prediction and a higher adherence to recent clinical guideline in general are measures that should be taken to optimise the prehospital treatment of stroke patients.

Pre-service Chemistry Teachers' Views about the Tentative and Durable Nature of Scientific Knowledge.

With regard to current controversial public discussions about the credibility of scientific knowledge, it seems particularly important that students possess adequate ideas about the tentativeness of scientific knowledge, which is a key aspect of nature of science. However, international studies show that many pre-service science teachers tend to have naïve conceptions about the tentativeness and these conceptions turn out to be resistant to change. So far, no research was done, on the conceptions of German pre-service chemistry teachers about tentativeness. Therefore, two empirical, qualitative research studies were conducted. The first study with 50 participants was to investigate, which conceptions about tentativeness German pre-service chemistry teachers possess, what the origins of these conceptions are and if they are resistant to change. In a second study with 56 participants, it was examined how a more adequate and functional understanding could be promoted. Data were collected by using different methods, such as open-ended questionnaires and semi-structured interviews. The participants' views about tentativeness were assigned to different categories. Results show that most participants held inconsistent or only partially informed views on tentativeness. The views turn out to be resistant to change, and many participants are not able to explain their ideas. And if so, their explanations are mostly restricted to scientific theories. Additionally, dealing with tentativeness unsettles some participants. To promote an adequate understanding, new approaches were developed, like the BlackTube activity. Additionally, instructions should focus on the durability of scientific knowledge. Furthermore, a differentiated reflection on different types of scientific knowledge seems necessary.

IABS/CEPI platform technology webinar: Is it possible to reduce the vaccine development time?

The International Alliance for Biological Standardization and the Coalition for Epidemic Preparedness Innovations organized a joint webinar on the use of platform technologies for vaccine development. To tackle new emerging infectious diseases, including SARS-CoV-2, rapid response platforms, using the same basic components as a backbone, yet adaptable for use against different pathogens by inserting new genetic or protein sequences, are essential. Furthermore, it is evident that development of platform technologies needs to continue, due to the emerging variants of SARS-CoV-2. The objective of the meeting was to discuss techniques for platform manufacturing that have been used for COVID-19 vaccine development, with input from regulatory authorities on their experiences with, and expectations of, the platforms. Industry and regulators have been very successful in cooperating, having completed the whole process from development to licensing at an unprecedented speed. However, we should learn from the experiences, to be able to be even faster when a next pandemic of disease X occurs.

Mu opioid receptor knockout mouse: Phenotypes with implications on restless legs syndrome.

Restless legs syndrome (RLS) is characterized by an irresistible need to move the legs while sitting or lying at night with insomnia as a frequent consequence. Human RLS has been associated with abnormalities in the endogenous opioid system, the dopaminergic system, the iron regulatory system, anemia, and inflammatory and auto-immune disorders. Our previous work indicates that mice lacking all three subtypes of opioid receptors have a phenotype similar to that of human RLS. To study the roles of each opioid receptor subtype in RLS, we first used mu opioid receptor knockout (MOR KO) mice based on our earlier studies using postmortem brain and cell culture. The KO mice showed decreased hemoglobin, hematocrit, and red blood cells (RBCs), with an appearance of microcytic RBCs indicating anemia. Together with decreased serum iron and transferrin, but increased ferritin levels, the anemia is similar to that seen with chronic inflammation in humans. A decreased serum iron level was also observed in the wildtype mice treated with an MOR antagonist. Iron was increased in the liver and spleen of the KO mice. Normal circadian variations in the dopaminergic and serotoninergic systems were absent in the KO mice. The KO mice showed hyperactivity and increased thermal sensitivity in wakefulness primarily during what would normally be the sleep phase similar to that seen in human RLS. Deficits in endogenous opioid system transmission could predispose to anemia of inflammation and loss of circadian variations in dopaminergic or serotonergic systems, thereby contributing to an RLS-like phenotype.

Design of customizable long linear DNA substrates with controlled end modifications for single-molecule studies.

Many strategies have been developed to manipulate DNA molecules and investigate protein-DNA interactions with single-molecule resolution. Often, these require long DNA molecules with a length of several 10s of kb that are chemically modified at specific regions. This need has traditionally been met by commercially available DNA from bacteriophage λ. However, λ DNA does not allow for the generation of highly customizable substrates in a straightforward manner, an important factor when developing assays to study complex biochemical reactions. Here we present a generalizable method for the design and production of very long chemically modified DNA substrates derived from a single plasmid. We show the versatility of this design by demonstrating its application in studying DNA replication in vitro. We anticipate this strategy will be broadly useful in producing a range of long chemically modified DNA molecules required for a diverse range of single-molecule approaches.

Coherently and fluorescence-detected two-dimensional electronic spectroscopy: direct comparison on squaraine dimers.

Optical two-dimensional electronic spectroscopy (2DES) is now widely utilized to study excitonic structure and dynamics of a broad range of systems, from molecules to solid state. Besides the traditional experimental implementation using phase matching and coherent signal field detection, action-based approaches that detect incoherent signals such as fluorescence have been gaining popularity in recent years. While incoherent detection extends the range of applicability of 2DES, the observed spectra are not equivalent to the coherently detected ones. This raises questions about their interpretation and the sensitivity of the technique. Here we directly compare, both experimentally and theoretically, four-wave mixing coherently and fluorescence-detected 2DES of a series of squaraine dimers of increasing electronic coupling. All experiments are qualitatively well reproduced by a Frenkel exciton model with secular Redfield theory description of excitation dynamics. We contrast the spectral features and the sensitivities of both techniques with respect to exciton energies, delocalization, coherent and dissipative dynamics, and exciton-exciton annihilation. Discussing the fundamental and practical differences, we demonstrate the degree of complementarity of the techniques.

Signatures of exciton dynamics and interaction in coherently and fluorescence-detected four- and six-wave-mixing two-dimensional electronic spectroscopy.

Two-dimensional electronic spectroscopy (2DES) can be realized in increasing nonlinear orders of interaction with the electric field, bringing new information about single- and multi-particle properties and dynamics. Furthermore, signals can be detected both coherently (C-2DES) and by fluorescence (F-2DES), with fundamental and practical differences. We directly compare the simultaneous measurements of four- and six-wave mixing C-2DES and F-2DES on an excitonic heterodimer of squaraine molecules. Spectral features are described in increasing orders of nonlinearity by an explicit excitonic model. We demonstrate that the four-wave-mixing spectra are sensitive to one-exciton energies, their delocalization and dynamics, while the six-wave-mixing spectra include information on bi-exciton and higher excited states including the state energies, electronic coupling, and exciton-exciton annihilation. We focus on the possibility to extract the dynamics arising from exciton-exciton interaction directly from the six-wave-mixing spectra. To this end, in analogy to previously demonstrated fifth-order coherently detected exciton-exciton-interaction 2DES (EEI2D spectroscopy), we introduce a sixth-order fluorescence-detected EEI2D spectroscopy variant.

DNA lesions correlate with lymphocyte function after selective internal radiotherapy.

In patients with non-resectable hepatic malignancies selective internal radiotherapy (SIRT) with yttrium-90 is an effective therapy. However, previous data indicate that SIRT leads to impaired immune function. The aim of the current study was to determine the extent of DNA lesions in peripheral blood mononuclear cells of SIRT patients and to correlate these lesions with cellular immune responses. In ten patients γH2AX and 53BP1 foci were determined. These foci are markers of DNA double-strand breaks (DSBs) and occur consecutively. In parallel, lymphocyte proliferation was assessed after stimulation with the T cell mitogen phytohemagglutinin. Analyses of vital cells were performed prior to and 1 h and 1 week after SIRT. 1 h and 1 week after SIRT numbers of γH2AX and of 53BP1 foci were more than threefold larger than before (p < 0.01). Already at baseline, foci were more abundant than published in healthy controls. Lymphocyte proliferation at baseline was below the normal range and further decreased after SIRT. Prior to therapy, there was an inverse correlation between lymphocyte proliferation and the quotient 53BP1/γH2AX; which could be considered as a measure of the course of DNA DSB repair (r = - 0.94, p < 0.0001). Proliferative responses were inversely correlated with 53BP1 foci prior to therapy and γH2AX and 53BP1 foci 1 h after therapy (r < - 0.65, p < 0.05). In conclusion, DNA foci in SIRT patients were correlated with impaired in vitro immune function. Unrepaired DNA DSBs or cell cycle arrest due to repair may cause this impairment.

Phosphoproteome Analysis Reveals Differential Mode of Action of Sorafenib in Wildtype and Mutated FLT3 Acute Myeloid Leukemia (AML) Cells.

Constitutively activating internal tandem duplication (ITD) alterations of the receptor tyrosine kinase FLT3 (Fms-like tyrosine kinase 3) are common in acute myeloid leukemia (AML) and classifies FLT3 as an attractive therapeutic target. So far, applications of FLT3 small molecule inhibitors have been investigated primarily in FLT3-ITD+ patients. Only recently, a prolonged event-free survival has been observed in AML patients who were treated with the multikinase inhibitor sorafenib in addition to standard therapy. Here, we studied the sorafenib effect on proliferation in a panel of 13 FLT3-ITD- and FLT3-ITD+ AML cell lines. Sorafenib IC50 values ranged from 0.001 to 5.6 µm, whereas FLT3-ITD+ cells (MOLM-13, MV4-11) were found to be more sensitive to sorafenib than FLT3-ITD- cells. However, we identified two FLT3-ITD- cell lines (MONO-MAC-1 and OCI-AML-2) which were also sorafenib sensitive. Phosphoproteome analyses revealed that the affected pathways differed in sorafenib sensitive FLT3-ITD- and FLT3-ITD+ cells. In MV4-11 cells sorafenib suppressed mTOR signaling by direct inhibition of FLT3. In MONO-MAC-1 cells sorafenib inhibited the MEK/ERK pathway. These data suggest that the FLT3 status in AML patients might not be the only factor predicting response to treatment with sorafenib.

Impaired lymphocyte function in patients with hepatic malignancies after selective internal radiotherapy.

The purpose of our study was to assess the immune function of patients with inoperable hepatic malignancies after treatment with selective internal radiotherapy (SIRT) and to identify possible correlations with clinical parameters. In 25 patients receiving SIRT lymphocyte proliferation and the production of pro- and anti-inflammatory cytokines (interferon-γ and interleukin-10) after stimulation with mitogens and microbial antigens were tested prior to therapy, directly after therapy (day 1) and at day 2, 7 and 28 post therapy using the lymphocyte transformation test and enzyme-linked immunospot assays. Absolute counts and percentages of leukocyte and lymphocyte subsets were determined by flow cytometry. The most prominent finding was an immediate and significant (p < 0.05) decrease of lymphocyte proliferation and interferon-γ production directly after therapy which lasted until day 28 and was stronger upon stimulation with microbial antigens than with mitogens. Moreover, lymphopenia was revealed, affecting all lymphocyte subsets (CD3+, CD4+, CD8+ T cells, CD4+ CD8+ T cells, B cells and NK cells). SIRT led to a reduction in the percentage of activated HLA-DR+ monocytes and of CD45R0+ memory T cells. Higher radiation activity, the presence of liver cirrhosis, chronic kidney disease, diabetes mellitus and metastases were unfavorable factors for immunocompetence, while a better Eastern Cooperative Oncology Group performance status was associated with stronger immunological reactions. In conclusion, SIRT leads to severe impairment of cellular in vitro immune responses. Further studies are needed to assess a potential clinical impact.

Patient and oncologist perceptions regarding symptoms and impact on quality-of-life of oral mucositis in cancer treatment: results from the Awareness Drives Oral Mucositis PercepTion (ADOPT) study.

PURPOSE: This descriptive cross-sectional survey aims to assess the level of concordance between the perspectives of oncologists and those of patients regarding oral mucositis (OM) symptoms, and the impact of OM on various aspects of daily living and concurrent cancer management. METHODS: Oncologists involved in OM management (n = 105), and patients who developed OM during cancer treatment (n = 175), were recruited from seven Asian countries. Oncologists completed a face-to-face, quantitative interview; patients completed a face-to-face interview, and a self-reported questionnaire. RESULTS: Oncologists and patients ranked treatment-induced OM among the three most important toxicities of cancer therapy requiring intervention. The most frequent OM symptoms reported by patients were oral ulcers (74%), dry mouth (73%), and difficulty swallowing (62%). Oncologists expected mild OM symptoms to last slightly longer than 1 week, whereas patients reported mild symptoms for more than 2 weeks. In mild-to-moderate OM, oncologists underestimated patients' pain experience. Overall, only 45% of oncologists said they would initiate OM prophylaxis when cancer therapy started. Of the 87% of patients who said they used their prescribed medications, only 16% reported using prophylactically prescribed medication. While oncologists' concerns related to the delays and interruptions of cancer treatment, patients tended to focus on the effects of OM on eating, drinking, and talking. CONCLUSIONS: Oncologists' and patients' perceptions about treatment-induced OM differ. To overcome discordant perspectives, there is a need to raise general awareness and improve proactive management of OM. As noted in recent guidelines, supportive cancer care is critical for ensuring optimal therapy and for improving the patient's experience.

Povidone-iodine ointment demonstrates in vitro efficacy against biofilm formation.

Anti-infectives used to treat chronic exuding wounds are diluted by wound exudates, absorbed into dressings, metabolised by proteases and destroyed by pH. In order to mimic such effects of exudates, the efficacy of six topical wound agents was assessed undiluted and at 10% concentrations, including povidone-iodine ointment and a silver-impregnated wound dressing, to remove biofilms of Pseudomonas aeruginosa, multi-species biofilms of Candida albicans and methicillin-resistant Staphylococcus aureus (MRSA) in vitro in a Centers for Disease Control and Prevention (CDC) reactor. Povidone-iodine was also diluted to 3·3% and 33·3% of the commercial concentrations. Viable microorganisms in each preparation were quantified by colony count. No viable P. aeruginosa biofilm material was recovered after 4 and 24 hours of treatment with povidone-iodine ointment at the 100% and 10% concentrations. No C. albicans/MRSA biofilm material was recovered after 4 and 24 hours of treatment with povidone-iodine ointment at the 100% concentration. In general, following dilution, povidone-iodine ointment appeared to exhibit greater biofilm removal than the other agents tested. Further research involving different microorganisms in vitro and in vivo over a longer period of time will help elucidate the full potential of povidone-iodine ointment and liposomal hydrogel.

Impairment of lymphocyte function following yttrium-90 DOTATOC therapy.

The radiolabeled somatostatin analogue, yttrium-90 DOTA-D-Phe(1)-Tyr(3)-octreotide (DOTATOC), is currently applied to treat advanced somatostatin receptor-positive tumors, e.g., neuroendocrine tumors of the pancreas, lung or gut. However, effects of this treatment on antimicrobial immune responses are not yet defined. In 20 patients treated with DOTATOC, cellular in vitro immune function was determined. Their antimicrobial lymphocyte responses were assessed by lymphocyte transformation test and enzyme-linked immunospot-measuring lymphocyte proliferation and on a single cell level production of pro- and anti-inflammatory cytokines (interferon-γ and interleukin-10)-prior to therapy, at day 1, day 7 and day 90 post-therapy. Proliferative lymphocyte responses and interferon-γ production after in vitro stimulation with microbial antigens were non-significantly suppressed at day 1 and significantly (p < 0.05) at day 7 versus pre-therapy. In vitro immune responses did not fully recover until day 90. In contrast, at day 1 interleukin-10 production was significantly (p < 0.05) increased. Taken together, we observed a decrease in pro-inflammatory immune responses after DOTATOC therapy. Patients with versus without bone metastases displayed significantly (p < 0.05) lower cellular immune responses toward several microbial antigens. Progressive disease and higher tumor burden could also be defined as factors associated with impaired immune function. Spearman correlation analysis indicated that cellular in vitro immunity was positively correlated with kidney function; better kidney function led to stronger immune responses. In conclusion, DOTATOC therapy caused a decrease in in vitro immune responses against microorganisms. The clinical impact needs to be evaluated in further studies.

In intermediate stage hepatocellular carcinoma: radioembolization with yttrium 90 or chemoembolization?

BACKGROUND & AIMS: Transarterial chemoembolization (TACE) is one of the standard treatments recommended for intermediate stage hepatocellular carcinoma (HCC). At the same time, only little is known about the use of radioembolization with Yttrium-90 microspheres (TARE Y-90) for this subset of patients. To perform comparative analysis between both locoregional therapies in intermediate HCCs. Primary endpoint was overall survival (OS), while safety, response rate and time-to-progression (TTP) were considered as secondary endpoints. METHODS: We collected data of 86 HCC patients in two university hospitals at which conventional TACE with doxorubicin or TARE Y-90 using glass microspheres were performed. The median observation period was 10 months. Patients were followed up for signs of toxicity and response. They underwent imaging analysis at baseline and follow-up at regular time intervals. RESULTS: Eighty-six HCC patients with intermediate stage B (BCLC) were treated with either TACE (n = 42) or TARE Y-90 (n = 44). Despite a higher tumour burden in the TARE Y-90 group, the median OS (TACE: 18 months vs. TARE Y-90: 16.4 months) and the median TTP (TACE: 6.8 months vs. TARE Y-90: 13.3 months) were not statistically different. The number of treatment sessions, the average rate of treatment sessions per patient, total hospitalization time and rate of adverse events were significantly higher in the TACE cohort. CONCLUSION: In intermediate HCC stage patients, both treatments resulted in similar survival probabilities despite more advanced disease in the TARE Y-90 group. Still, TARE Y-90 was better tolerated and associated with less hospitalization and treatment sessions.

Safety and Efficacy of Selective Internal Radionuclide Therapy with 90Y Glass Microspheres in Patients with Progressive Hepatocellular Carcinoma after the Failure of Repeated Transarterial Chemoembolization.

Transarterial chemoembolization (TACE) is currently the standard of care in patients with unresectable hepatocellular carcinoma (HCC), and selective internal radionuclide therapy (SIRT) with 90Y microspheres is mainly used as an alternative modality in patients considered poor candidates for TACE. Treatment with sorafenib is the recommended option for patients with progressive disease after TACE. This study aims to evaluate the safety and efficacy of SIRT with glass microspheres in patients with progressive HCC after repeated TACE who are not eligible for treatment with sorafenib. Forty-seven patients with progressive HCC after a median of three TACE sessions (range 2-14) underwent SIRT (3.5 ± 1.5 GBq; liver target dose 110-120 Gy). Toxicity was recorded 4 and 12 weeks after treatment and reported according to the Common Terminology Criteria for Adverse Events Version 5.0. Treatment response was assessed three months after SIRT using multiphase computed tomography and modified criteria in solid tumors (mRECIST). Survival analyses were performed using Kaplan-Meier curves and a Cox proportional hazards model for uni- and multivariate analyses. Significant but reversible hepatotoxicity (≥grade 3) occurred in five patients (11%). No radioembolization-induced liver disease (REILD) was observed. The number of previous TACE sessions and cumulative administered activity did not predict the incidence of post-SIRT significant hepatotoxicity. Treatment responses consisted of partial responses in 26 (55%), stable disease in 12 (26%), and progressive disease in 9 (19%) patients. The median overall survival (OS) was 11 months (95% confidence interval (CI), 9-13), and objective responses to SIRT were associated with a longer OS (p = 0.008). Significant hepatotoxicity (≥grade 3) after SIRT was a contributor to impaired survival (median OS 6 months (95% CI, 4-8) vs. 12 months (95% CI, 10-14), p < 0.001). SIRT with glass microspheres is a safe and effective salvage treatment for patients with progressive HCC refractory to TACE who are considered poor candidates for sorafenib treatment.